Golf ball made from a vulcanized elastomer composition



United States Patent US. Cl. 273-218 8 Claims ABSTRACT OF THE DISCLOSUREA golf ball made from a unitary solid elastomer prepared by vulcanizinga composition consisting essentially of highly resilient polybutadieneelastomer, trimethylol propane trimethacrylate, a white pigment, afiller material, and a cross-linking agent such as dicumyl peroxide.

This application is a continuation-in-part of my own prior applicationSer. No. 317,052 filed Oct. 17, 1963, now abandoned.

The present invention relates to golf balls, and to new and improvedcompositions for forming a golf ball, which ball is made from a unitaryelastomer body having a substantially uniform composition throughout.

At the present time, all high quality balls are made from severaldifferent components which usually include a center, some type of arubber or elastomer strip or thread that is wound around the center andcompletely encloses the center, and a finish cover that is molded as anintegral unit around the wrapped center of the ball. Some efforts havebeen made heretofore to provide a unitary or homogeneous type of a golfball but all of such previous efforts have only provided, insofar as Iam aware, a low quality ball having relatively poor properties.

It is relatively well known that golf balls are subjected to very severestresses when used. Thus one test report, for example, has indicatedthat a golf club head may be moving at a speed approximately 166 ft. persecond when it strikes the ball, and that the ball, for a good drive,for example, would leave the club head after momentary impact therewithat a speed of approximately 170 miles per hour. The club head has beenmeasured to be in contact with the golf ball for approximately .0005second and the golf ball is believed to absorb energy at the rate ofabout 300 horsepower in the brief contact between the club head andball. The ball may have a spin of as much as 3500 to 4000 rpm. or moreimparted thereto at the moment of impact, and the club is believed toexert as much as a /2 ton impact on the ball when it is struck.

In all events, high quality golf balls as in use today are made to highstandard and have costly materials and forming operations used to makeand assemble the centers, windings, and covers thereof. These balls havespecified limits as to their sizes and weights, which limits must bestrictly complied with if the ball is to have approval of the governingbodies in golf play, such as United States Golf Association.Furthermore, all good golfers recognize quality balls in most instancesby the very pleasant sounding click that is obtained when a golf ball isproperly struck by a club, such as a driver, and for acceptance of a newball, it must have a sound comparable to that of relatively expensive,high quality balls of previously known construction.

Therefore, it is the general object of the present invention to providea new and improved high quality, unitary golf ball of a substantiallyuniform composition throughout, which golf ball is primararily made fromhighly resilient polybutadiene rubber elastomers having a methacrylatemonomer included therein.

3,502,338 Patented Mar. 24, 1970 "ice A further object of the inventionis to provide a new and improved composition for use in making integralor unitary types of golf balls therefrom and where the compositionincludes polybutadiene elastomer having an appreciable cis configurationdouble bond content, trimethylol propane trimethacrylate, and a peroxidecuring agent therein.

A further object of the invention is to provide a unitary substantiallyhomogeneous composition golf ball that includes a highly resilientpolybutadiene rubber elastomer and which ball has good compressioncharacteristics, a relatively high durometer, a high reboundcharacteristic, and which has a click sound very comparable to that ofrelatively expensive high quality balls in use today and made fromcenters, separate windings and molded covers formed integrally aroundthe wrapped ball center.

A further object of the invention is to provide a new and improved golfball of a unitary construction throughout and which golf ball has highresistance to cutting or marring of the periphery of the golf ball, andwhich ball has high quality characteristics of play when in use.

The foregoing and other objects or advantages of the invention will bemade more apparent as the specification proceeds.

The present invention, in one embodiment thereof, relates to theprovision of a golf ball made from a unitary, solid, elastomer made byvulcanization of a composition consisting essentially of the followingingredients in substantially the ratios stated: polybutadiene rubberabout 100 parts, trimethylol propane trimethacrylate about 20 to 70parts, a peroxide curing agent about 0.5 to 10 parts, a finely dividedreenforcing pigment about 20 to 60 parts, and a white pigment about 2 to15 parts, as maximum ranges of the golf ball composition.

In making the new and improved golf ball of the invention, the ball ismade primarily from an elastomer comprising 1,4-polybutadiene rubber,which in the compositions stated hereinafter will be used normally asincluding such elastomer in about 100 parts by weight and the remainingingredients of the composition and ball produced then can be variedwithin predetermined limits set forth in relation to this basicelastomer mass. A methacrylate monomer is used between about 20 to 70parts by weight preferably in the more limited range of 25 to 55 parts,and specifically the monomer or ester SR350 which is trimethylol propanetrimethacrylate is used.

Cis-type polybutadiene rubber, or elastomer used in practice of theinvention is a highly resilient polybutadiene rubber made in a solutionpolymerization process usually using a stereo-specific catalyst system.

Patents referring to processes for providing synthetic polymers of thetype for use with the present invention include British Patent No.827,365, US. Patent No. 3,178,402, and Belgium Patents 551,851; 573,680and 575,671.

Yet other discussions on rubbers of the general type for use in practiceof the invention are found in a paper entitled, Dione Rubber: A LinearPolybutadiene, which was given at the International Congress sponsoredby the German Rubber Society on Oct. 5, 1960, in West Berlin, Germany,which paper was presented by Glen Alliger, V. L. Johnson, and L. E.Forman, and as an article starting on page 276 of the March, 1961, issueof Rubber and Plastics Age.

These cis-types of polybutadienes may have some appreciable variation inthe number of double bonds in the polymer molecule arranged in the cisconfiguration and such double bond arrangement usually predominates inthese elastomers and with this cis-type configuration being presentusually in from about 50% to 60% up to or more. However, some of thepolybutadiene elastomers of this general type may have a predominantlytrans-type of double bond configuration and be useful in the practice ofthe present invention as long as they have, for example, at least about30% cis double bond content out of 100 double bonds. One commercialelastomer which has been used in practice of the invention is termedCis-4 rubber and is generally described in U.S. Patent No. 3,178,402.The elastomers may have a small amount such as up to 2 or 3% of 12configuration present therein.

The composition also includes a cross-linking agent in the form of aperoxide, particularly the material DiCup 40C which comprises dicumylperoxide. This material can be used in the range of from about 0.5 toparts by weight and preferably in the range of about 2 to 8 parts forbest results and this substance comprises about 40% active material.Other peroxides or peroxys that may be used in practice of the inventionfor the dicumyl peroxide would be 2,4-dichloro-benzoyl peroxide (50% mixwith 50% inert filler); 2,5-dimethyl-2-5-di (t-butyl-peroxy) hexane 45%mix with 55% inert filler; or 2,5 dimethyl-2,5-di (t-butyl-peroxy)hexane 3 (43% strength with 57% inert filler), or 90% strength with 10%inert filler.

A finely divided reenforcing pigment, in this instance preferably aWhite, hydrated silica powder such as HiSil 233 is used and it, or itsequivalent, may be used in from about to 60 parts by weight andpreferably is present in the composition between about to 45 parts byweight. With increasing amounts of the HiSil 233 being used in the rangestated, it provides higher compression and hardness in the resultantgolf ball but lowers the rebound characteristics of the ball. HiSil 233is a precipitated hydrated silica of very fine ultimate particle sizeand it comprises about 89.2% of silicon dioxide and small amounts ofother materials. It has a particle size of approximately 0.022 micron.

While one particular type of hydrated silica has been referred to informing the improved golf ball composition of the invention, variousother known types of fillers, preferably white, can be used in makingthe composition of the invention so that thus other type of silicas,such as Silene EF, can be used, while wood filler, barytes, andequivalents can be used in making the composition of the invention. Thefillers used are conventional and aid in weight control and strength ofbond. Usually the smaller the particle size, the easier it is to processand disperse the filler with the batch and the more effective the filleris for a given total weight.

Another suitable filler includes Dixie Clay which is an inert hardkaolin clay. Silene EF is a hydrated silicate comprising about 65%silica, about 19.5% lime, small amounts of other oxides and salt and theremainder water of hydration. The fillers preferably are of a size topass through U.S. Standard screen size, No. 325, and some are fineenough to pass through screen size No. 400. The fillers may be usedindividually or two or more fillers may be used in combination withinthe ranges stated.

One good method of adjusting the weight of the molded product is to varythe amount of titanium dioxide used. Some size variations may becompensated for by the painting or finishing of the balls.

When increased amounts of the acrylates are used, the resultant golfball produced tends to have higher compression and hardness andvariation in the amount of such material used within the range stateddoes not appear to reduce the rebound characteristics of the ballobtained more than a few percent.

To aid in improving the color of the ball, and to improve itscharacteristics in general, appreciable quantities of titanium dioxideare used in the composition, usually from about 2 to 15 parts by weightof this material being suitable but with from about 4 to about 10 partsbeing preferred. Hence, the amount of white pigment used can beconsidered to have a range of from about 22 to about 75 parts by weightand the amount of HiSil or equivalent and titanium dioxide used can varywithin such range.

Specifically, a very satisfactory golf ball has been produced from thecomposition consisting essentially of 1,4 polybutadiene about 100 partsby weight, trimethylol propane trimethacrylate about 55 parts by weight,titanium dioxide about 15.0 parts by weight, HiSil about 30 parts byweight, and dicumyl peroxide about 2.5 parts by weight. This golf ballproduced from the above formula had a compression of 86 under thestandard United States Golf Association test, and had a durometer of 58on the Shore D scale, had a rebound of 73 inches out of a 100 inch drop,and had a click that was very good and comparable to that of relativelyexpensive, or costly quality golf balls in use today and made from aseparate center, winding, and cover. In this golf ball composition, ablue color or pigment material, such as ultramarine blue, may be addedto .4 part by weight. This aids in improving the whiteness of theresultant products.

In some instances, it is possible to use the golf ball of the inventionwithout applying any coating or painting thereto, but preferably anysuitable paint may be applied to the ball, and be dried thereon, afterthe ball has been molded. The various ingredients of the elastomercomposition of the invention can be mixed in conventional manners, andthen be extruded through known equipment into a strip form after whichsections of the strip can be severed in the desired quantities and beindividually placed in suitable compression molds for production of thefinished products. The actual composition set forth hereinabove has beensatisfactorily cured in 18 minutes at 320 F.

The golf ball of the invention has had a rebound characteristic that isvery comparable to that of high quality balls, and this test usually isperformed by dropping the ball onto a hard rebound surface, such as amarble plate or block, and the golf ball when used or tested has a verysatisfactory sound pleasing to the ear of the golfer accustomed to highquality golf balls as made and sold today.

EXAMPLE 2 Parts by weight Highly resilient polybutadiene 100 SR350 45HiSil 30 DiCup, 40C 3.75 TiO 6.00 Ultramarine Blue .01

EXAMPLE 3 Parts by weight In this example, the polybutadiene, fattyacid, resin 8318, and naphthenic oil are premixed and then 2.50 parts ofthe premix, modified polybutadiene, are used in the composition as anaid to processing. The modified polybutadiene elastomer of Example 3includes a suitable fatty acid, such as stearic acid, and about 3 partsof an alkylphenol novolak type resin (resin 8318) mixed therewith. Thepolybutadiene used in Example 3 had a high cis content of over Smallpercentage composition by weight of styrene type resins or elastomersmay also be used in the formula used in forming the golf balls of theinvention. Such styrene resins are commercially known today and comprisea copolymer of between about 70 to 90% of styrene and from about 30 tobutadiene. Such resins are unsaturated and are vulcanizable. They seemto increase the strength and hardness of the finished composition. Also,the resin improves the click of the ball produced. Use of the premix andstyrene resin facilitates the processing and molding of the composition.Satisfactory golf balls, meeting U.S.G.A. standards, were made andtested using the formulations of Examples 2 and 3.

One specific reenforcing filler, or pigment, used in practice of theinvention is HiSil 233.

Other compositions for practice of the invention include:

Material R R9 RRS RR43 R R44 RR45 R R131 RR132 Cis 4 polybutadiene- 100.0 100. 0 95. 0 95. 0 95. 0 91. 0 91.0

Styrene resin 2. 50 2. 50 2. 50 4. 50 4. 50

The CB-880 material noted in the above examples is a modified cis-typepolybutadiene that is a relatively easy processing material. It is thesame material as the premix set forth in Example 3 hereinbefore. Thecoloring material was ultramarine blue in the above examples and thestyrene resin used is as described hereinbefore. In the CB-880, smallquantities of the modifying ingredients are present preferably in aboutthe quantities indicated but changes of about one part plus or minusfrom the quantities stated for forming the premix can be made and goodresults are still secured.

Compositions of invention consisting essentially of:

The rebound characteristics of a golf ball are believed to be improvedappreciably when the trimethylol propane trimethacrylate has been usedin combination with the dicumyl peroxide. While some variation in theingredients and compositions stated hereinbefore are possible, thepreferred composition is set forth hereinabove and has given the bestresults in tests of golf balls produced from these new compositions ofthe invention.

From the foregoing, it is believed that it will be seen that the objectsof the invention have been achieved.

While one complete embodiment of the invention has been disclosedherein, it will be appreciated that modification of this particularembodiment of the invention may be resorted to without departing fromthe scope of the invenion as defined in the appended claims.

What is claimed is:

1. A golf ball comprising a spherical unitary, solid elastomer made byvulcanization of the following composition consisting essentially of thefollowing ingredients in the weight ratios stated:

a highly resilient polybutadiene rubber having a cis configurationinternal double bond of at least 30% of about 100 parts.

about to 70 parts of trimethylol propane trimethacrylate,

an organic peroxide curing agent about 0.5 to 10 parts,

finely divided reenforcing pigment about 20 to 60 parts,

and

a white pigment about 2 to 15 parts.

2. A golf ball formed. from a composition as in claim 1 where saidperoxide curing agent is a material from the class consisting of dicumylperoxide, 2,4 dichlorobenzoyl peroxide, 2,5dimethyl-Z-S-di(t-butyl-peroxy) hexane 45 and 2,5dimethyl-2,5-di(t-butylperoxy)hexane 3 (43% strength with 57% inertfiller), or 90% strength with 10% inert filler.

3. A golf ball formed from a composition as in claim 1 where from 25 to55 parts of trimethylol propane trimethacrylate are used.

4. A golf ball comprising a composition as in claim 1 wherein saidhighly resilient material including an unvulcanized polybutadieneelastomer includes up to about 3% of 1-2 configuration double bondstherein.

5. A golf ball comprising a spherical unitary, solid elastomer made byvulcanization of the following composition consisting essentially of thefollowing ingredients in the weight ratios stated:

a highly resilient conjugated diene elastomer consisting essentially ofmaterial having a cis configuration internal double bond above 30% ofabout 100 parts,

about 25 to 55 parts of trimethylol propane trimethacrylate,

a peroxide curing agent from the class consisting of dicumyl peroxide,2,4 dichlorobenzoyl peroxide, 2,5 dimethyl-2,5-di(t-butyl-peroxy) hexane45%, and 2,5 dimethyl 2,5 di(t butyl-peroxy)hexane 3 (43% strength with57% inert filler), or 90% strength with 10% inert filler about 2 to 8parts,

finely divided white reenforcing pigment about 30 to 45 parts, and

titanium dioxide about 4 to 10 parts.

6. A golf ball comprising a spherical unitary, solid, elastomer made byvulcanization of the composition consisting essentially of the followingingredients in the weight ratios stated:

a highly resilient material when vulcanized consisting essentiallyinitially of conjugated polyolefin hydrocarbon elastomer having a cisconfiguration of internal double bonds above about 30% of about 100parts,

about 20 to parts of trimethylol propane trimethacrylate,

a peroxide curing agent from the group consisting of dicumyl peroxide,2,4 dichlorobenzoyl peroxide, 2,5 dimethyl-Z-S-di(t-butyl-peroxy) hexane45%, and 2,5 dimethyl-2,5-di(t-butyl-peroxy) hexane 3 (43% strength with57% inert filler), or strength with 10% inert filler about 0.5 to 1-0parts,

a finely divided hydrated silica powder about 20 to 60 parts, and

from about 2 to about 15 parts of titanium dioxide.

7. A golf ball formed from a composition as in claim 1 where the whitepigment comprises titanium dioxide.

8. A golf ball formed from a composition as in claim 1 where the finelydivided reinforcing pigments include at least one material from theclass consisting of hydrated silica powder, silicas, wood filler,barytes, hydrated silicates, and inert hard kaolin clay, and having aparticle size to pass through US. Standard screen size No. 325.

References Cited UNITED STATES PATENTS 3,239,228 3/1966 Crompton 260-4153,241,834 3/1966 Stingley 260-415 3,313,545 4/1967 Bartsch 260-415 ALLANLIEBERMAN, Primary Examiner US. Cl. X.R. 260-415 UNITED STATES PATENTOFFICE CERTIFICATE OF CORRECTION Patent; No, 38 Dated March 24, 1970Inventor) Alvon R. Cox

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 6 line 16, ".4 part" should read .04 part Signed and sealed this18th day of August 1970 (SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting OfficerCommissioner of Patents I FORM powso (10459) USCOMM-DC soanmoa i U SGQVIINMKNT 'RlNTIKG OFFICE I". o"'3'l,

